De Bruijn Graph Assembly

When our lab got its first metagenomic dataset, the first thing we did was upload our QC filtered and merged paired-end Illumina reads (mean length 160 bp) onto MG-RAST for annotation.  However, when the annotations came back, some organisms whose genomes were known to be present in both our sample and the m5nr reference dataset were missing and, for those sequences that were annotated, the designated e-values centered around 1e-10.  In order to improve the annotation of our data, we decided to perform an assembly.   Searching the literature, I found that a class of assemblers — called De Bruijn Graph assemblers — were the popular choice for assembly of short read metagenomic data; however, the intuition behind how these assemblers worked was a little less clear. Continue reading

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